One-shot signatures

Consider the following three questions:

- Alice sends messages separately to Bob and Charlie. Can Bob and Charlie, without communicating, be assured that Alice sent both of them the same message?

- Is it possible to transmit interesting quantum states with only classical communication?

- Are cryptographic hash functions built using quantum-resistant tools necessarily secure against quantum attacks?

A one-shot signatures (OSS) — a new tool from quantum cryptography — gives perhaps surprising answers to these questions. In this talk, I will explain the concept of OSS, discuss a number of interesting applications, and sketch how to construct it.